Introduction

The odontoid process, also called the dens, is a bony part that sticks out from the second bone in the neck, known as C2 or the axis. It helps keep the neck steady and allows one to turn and bend one's head. Odontoid fractures are also known as dens fractures.

Odontoid fractures are a significant issue in spine injuries, especially for older individuals. They comprise about 20 percent of adult cervical spine fractures and are the most common type in people over 65. These fractures usually happen at the second cervical vertebra, accounting for half of all C2 fractures. This injury has two peak age groups: younger adults and the elderly.

What Are the Causes of Odontoid Fractures?

The cause of odontoid fractures depends on the force applied and the quality of the bone. In younger people, high-impact events can lead to these fractures, while even minor incidents can result in older individuals. These fractures occur because the neck moves too far backward (hyperextension) or forward (hyperflexion).

• Traumatic Injuries - Odontoid fractures are commonly associated with traumatic injuries. The abrupt and forceful movement of the neck can lead to a fracture of the odontoid process. Vehicle accidents, sport-related injuries, and falls are the common injuries that cause these fractures.

• Age-Related Degeneration - In some cases, odontoid fractures can occur due to age-related degeneration of the cervical spine. As individuals age, the spine's bones may become weaker and more susceptible to fractures. This is especially true for those with conditions like osteoporosis.

• Medical Conditions - Some medical conditions, like tumors or rheumatoid arthritis affecting the cervical spine, can also predispose individuals to odontoid fractures.

How Are Odontoid Fractures Classified?

Odontoid fractures are categorized into three main types.

1. Type I Fractures: This is a fracture of the very tip of the odontoid process and is often considered stable.

2. Type II Fractures: These are the most common type of odontoid fractures and occur at the base of the odontoid process, near the junction of C2 and C3. Type II fractures are usually more unstable than Type I fractures.

3. Type III Fractures: Type III fractures involve a fracture line extending through the body of the axis (C2), making them the most unstable of the three types.

What Are the Symptoms of Odontoid Fractures?

The symptoms of odontoid fractures can vary depending on the type of fracture. Symptoms of odontoid fractures also vary between younger and older patients. Younger individuals typically have these fractures after significant accidents like car crashes or sports injuries, and they usually remember the trauma. In contrast, older people can experience these fractures from minor incidents, like a simple fall or bumping into something.

Common symptoms of odontoid fracture include:

• Neck pain increases when one moves one's neck.

• Limited range of motion in the neck.

• Sometimes, the patient may have difficulty swallowing due to a hematoma or swelling in the throat area.

• Occasionally, patients might experience issues with their spinal cord, such as tingling, weakness in their arms or legs, or other problems with their nerves.

• Muscle weakness.

• Difficulty breathing in severe cases.

• Spinal cord injuries are less common in odontoid fractures because the spinal canal at the level of the odontoid process is relatively spacious compared to the size of the spinal cord.

How Is an Odontoid Fracture Diagnosed?

Medical professionals may use a combination of imaging studies to diagnose an odontoid fracture, including X-rays, CT (computed tomography) scans, and MRI (magnetic resonance imaging) scans.

• X-rays for diagnosing odontoid fractures include lateral, anterior-posterior (AP), and open-mouth views of the cervical spine. Flexion-extension X-rays may also be taken if there is a suspicion of instability at the top of the neck.

• A CT spine scan provides the best resolution for assessing the bone structure, making it excellent for identifying and characterizing odontoid fractures. It is also helpful in recognizing anatomical abnormalities, like issues with the posterior arch of the first cervical vertebra (C1). This information is vital for planning treatment strategies.

• CT angiography may be necessary in cases where the fracture extends near blood vessels or to assess the course of the vertebral artery during posterior fixation.

• MRI is used to evaluate the transverse ligament and spinal cord condition in patients with neurological deficits. It is valuable for assessing soft tissues and potential spinal cord or ligament damage.

How Are Odontoid Fractures Managed?

Treatment for odontoid fractures aims to achieve stability, the primary goal.

Conservative Treatment - A traditional approach may be suitable in cases with good alignment, no dynamic instability, and no deficits. This involves using a rigid brace or halo vest to promote healing. Type I and Type III fractures can often be treated this way. A cervical collar is better than a halo vest, especially for older patients, as it has fewer complications.

Surgical Treatment

• Open Reduction and Internal Fixation: Type II fractures usually need surgery. The process includes cutting the neck open, repositioning the fractured bone, and securing it with screws and plates.

• C1-C2 Fusion: In some cases, fusion of the C1 and C2 vertebrae may be necessary to stabilize the fracture site. This procedure involves using bone grafts and hardware to create a solid fusion between the two vertebrae.

• Transoral Odontoidectomy: In cases where the fracture is complex or non-reducible, a transoral odontoidectomy may be performed, which involves removing the fractured part of the odontoid process through the mouth.

What Are the Complications of Odontoid Fractures?

Complications that can arise from odontoid fractures include:

• In some cases, the fractured bone may not fully heal or fuse. This can lead to ongoing instability and pain.

• If the fracture damages the spinal cord or nerves, it can result in permanent neurological deficits.

• Severe odontoid fractures can lead to breathing difficulties, as the cervical spine supports the airway.

The long-term outlook for individuals with odontoid fractures varies depending on various factors. If surgery is performed within six months of the injury, there is an 88% chance of successful fusion. People with stable fractures and successful treatment can expect a good recovery with proper rehabilitation.

What Can Be Done to Prevent Odontoid Fractures?

Preventing odontoid fractures often involves injury prevention measures, such as:

• Wearing seatbelts while driving and helmets when participating in sports.

• Taking steps to prevent falls, especially among the elderly.

• Managing medical conditions that weaken the bones, like osteoporosis.

• Seeking treatment for conditions that affect the cervical spine.

Conclusion

Odontoid fractures can pose challenges, but with improvements in healthcare and therapy, many patients can become stable again and resume a satisfying life. Doctors and patients need to be careful, especially when it comes to injuries in the neck. Acting quickly and using a thorough approach to treatment can greatly improve the chances of getting better.